Just wondering if all 4 cylinders are within spec...

 

Hey, it’s been a while but I finally decided to go out to harbor freight and pick up a compression test kit. I got for the results this:
1 130

2 145

3 145

4 135

It looks good to me, so I decided to buy a new maf sensor since it was only going up to 15 g/sec at around 4-5krpm and I read somewhere else it should be at 15 g/s at 2500rpm (10 at 2500). If that’s not the issue, I guess maybe it could be a catalytic converter going bad or coil packs maybe. I feel something vibrating underneath the car when driving so it might be the cat or just my shocks (they are still the original sport suspension). Exhaust smells like raw gas in first 2 or so min of running, but doesn't really smell of rotten eggs after that

Let me know if you guys have any other ideas, thanks for the help so far!

 

1) I decided to buy a new maf sensor since it was only going up to 15 g/sec at around 4-5krpm and I read somewhere else it should be at 15 g/s at 2500rpm (10 at 2500).
Replace the sensor if it's out of spec.
Or is there an air leak before the sensor ?
2) I guess maybe it could be a catalytic converter going bad or coil packs .
Why ? Are there any codes that could relate to these two problems ?
3) I feel something vibrating underneath the car when driving so it might be the cat or just my shocks (they are still the original sport suspension).
If it's the Cat hit with a hammer and listen to it. Shock don't vibrate unless you mean the wheels are bouncing up and down like a balancing issue.
Start with the known problem and stop chasing your tail with the maybe's.

 

More diagnostic work, before throwing cash at 'maybe parts'.

 

Okay, got the new MAF sensor, did not fix the issue and it kept the airflow rate at the same exact as before. Going over the causes again:

The MAF (Mass Air Flow) Sensor is dirty or faulty. - Replaced, not the issue
There could be a vacuum leak. - See no vacuum leaks, it is going into a closed loop also I believe (fuel trim at 0.999)
There could be a fuel pressure or delivery problem - The fuel injectors are new, sprayed them with carb cleaner and the RPMs didn't change. I once again checked the fuel pressure while it was running, it jitters at 60 psi a few psi but always stayed there for the 5-10 min I ran it. Kept the pressure gauge on for 5-10 min after turning off the car, it stayed at 60 psi. No visible cracks in the exhaust manifold or flex pipe, but I will lift the car up soon to double-check everything. Purge valve solenoid is new. Coolant temp sensor is fine


The check engine light always turns on when I let it idle, but then turns off as I drive it. There is some difficulty in accelerating the car when in any gear higher than second.

I'm assuming that the P0172 code is the cause of the P0300 code, but I've had P0304 show up instead of P0300 on two occasions which then turns into P0300. If I'm wrong, are there any ways a cause of a P0300 code can cause a P0172 code?

 

That pretty much leaves vacuum leak, inspect the power brake booster and hose to the intake, double check the throttle body gasket, did you replace the fuel injector insulators and all O-rings? And for fun if you disconnect the under hood EVAP valve can you blow air through it, it should be closed and no air should pass through it .

 

Checked the vacuum and it was fine. I brought it to my mechanic to look at and he said it might have skipped a tooth. I am going to take off the valve cover today and check the timing marks. I think it might have jumped because the tensioner may have not been torqued exactly to spec (a little under). I don’t know why I didn’t torque it to spec all the way. If that is the issue, what’s the best way to go about moving the chain? Removing the tensioner along with the large guide and then repositioning it? I’ll check the other chain to see if off timing too but I think that one will be fine.

 

Removing only the valve cover will allow you to check if the timing chain is loose. To see if the engine is timed correctly, you will also have to remove the crank pulley and timing cover. If the timing is off, you will have to remove the tensioner and, I believe, one of the camshaft sprockets.

How did you check for vaccum leaks?

 

Remove the tensioner first, Remove the exhaust camshaft sprocket, to reset the chain.

 

Knowing what code is active when the CEL is on would help. ASSuMeing is not helpful.

P0172/P0171 won't clear itself until the next driving cycle.